• The Korean Journal of Pain
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• v.37 no.1
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• pp.59-72
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• 2024

Background: This study assessed the postoperative analgesic efficacy and safety of the quadratus lumborum block (QLB) in pediatric patients. Methods: Electronic databases were searched for studies comparing the QLB to conventional analgesic techniques in pediatric patients. The primary outcome was the need for rescue analgesia 12 and 24 hours after surgery. Secondary outcomes covered the Face-Legs-Activity-Cry-Consolability Scale (FLACC) scores at various time points; parental satisfaction; time to the first rescue analgesia; hospitalization time; block execution time; block failure rates, and adverse events. Results: Sixteen randomized controlled trials were analyzed involving 1,061 patients. The QLB significantly reduced the need for rescue analgesia both at 12 and 24 hours after surgery (12 hours, relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.01, 0.88; 24 hours, RR: 0.51; 95% CI: 0.31, 0.70). In case of 24 hours after surgery, type 1 QLB significantly reduced the need for rescue analgesia (RR: 0.56; 95% CI: 0.36, 0.76). The QLB also exhibited lower FLACC scores at 1 hour (standardized mean difference [SMD]: -0.87; 95% CI: -1.56, -0.18) and 6 hours (SMD: -1.27; 95% CI: -2.33, -0.21) following surgery when compared to non-QLB. Among QLBs, type 2 QLB significantly extended the time until the first rescue analgesia (SMD: 1.25; 95% CI: 0.84, 1.67). No significant differences were observed in terms of parental satisfaction, hospitalization time, block execution time, block failure, or adverse events between QLB and non-QLB groups. Conclusions: The QLB provides non-inferior analgesic efficacy and safety to conventional methods in pediatric patients.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.157-164
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• 2012

When designing a multifunctional system consisting of many components performing many functions or missions, it is important to determine the reliability, availability, and maintainability (RAM) of the system and components, and we consider system availability to be the optimization criterion. For given intervals of mean time between failure (MTBF) and mean time to repair (MTTR) of the components, we want to determine the values of MTBF and MTTR for all components that satisfy the target availability. A heuristic method is proposed for finding near-optimal solutions through simulation. We also study numerical examples to check effects of model parameters on the optimal solutions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4893-4901
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• 2013

In order for a machine, especially used in the defense industry, to consistently operate during its life-time, lots of study has been done in machine design as well as machine maintenance. However, the realistic study is necessary in management and operation of a military support facility, where spare parts are stored and retrieved. In this paper, efficient arrangement of spare parts are proposed to acquire increased in efficiency and decreased in cost for operation management of the military support facility. First, spare parts is assorted by MTBF(Mean Time Between Failure) and divided in to three groups A/B/C as an alternative arrangement. Each defined alternatives will go under simulations and RULA(Rapid Upper Limb Assessment), which is posture classification scheme evaluation attributes, to find working time and posture difficulty and lastly by entropy measurement to be selected. This research proposes the efficient spare parts arrangement in military support facility to minimize working time and posture difficulty. By taking system and human engineering approach together into consideration, it will lead to show a specific value.

• Journal of Korean Society for Quality Management
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• v.22 no.1
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• pp.113-121
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• 1994

Present worth of warranty cost for an irrepairable item is derived under free-replacement, prorata and hybrid warranty policies, respectively. In this paper, it is assumed that the lifetime distribution is a Gamma, and warranty period is not renewed but maintained as promised at the selling time regardless of replacements due to warranty contract. A numerical example on the relationship between present worth of warranty cost and mean time to failure is included.

• Journal of Chest Surgery
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• v.18 no.1
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• pp.54-61
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• 1985

One-hundred-and-seven patients were the consecutive cases of double replacement of the mitral and the aortic valves at the same time using the lonescu-Shiley bovine pericardial xenograft valve during the period between May, 1979 and June, 1984. They were 64 males and 43 females, and their ages ranged from 13 to 62 years [mean age, 34.011.9 years]. Eight patients died within 30 days after surgery [operative mortality rate, 7.5%], and 7 others thereafter [late mortality rate, 6.5%; or 4.21%/patient-year]. Ninety-nine early survivors were followed up for a total duration of 166.1 patient-years [mean duration, 20.116.1 months]. Two patients experienced thromboembolic complication with no death [1.20%/patient-year]; five developed prosthetic valve endocarditis [3.01%/patient-year] with one death; and three had a new development of aortic regurgitant murmur and they were, along with a mortality from endocarditis, classified into the cases of tissue valve failure [2.41%/patient-year]. The actuarial survival rate including the operative mortality was 82.24.7% at 6 years after surgery. The probabilities of freedom from thromboembolism and from valve failure were 97.61.7% and 88.67.6% at 6 years respectively. Symptomatic improvement was excellent in most of the cases at the follow-up end, showing the mean of the postoperative NYHA Classes of 1.120.33 from the preoperative one of 2.860.54. These results compares favorably with the ones reported from the major institutions. Clinical results of isolated replacement of the mitral valve and of the aortic valve were previously reported. The clinical results of a total and consecutive patients with replacement of single mitral and single aortic and double mitral and aortic valves on the mortality rate, survival rate, complication frequency, and symptomatic improvement all fully stands for the good therapeutic modalities of the valvular heart diseases with severely damaged lesions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.27.1-27.9
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• 2019

Background: Implants are becoming the first choice of rehabilitation for tooth loss. Even though they have a high success rate, failures still occur for many reasons. The objective of this study is to analyze the reasons for recurring failure at the same site and the results of re-implantation. Methods: Thirteen patients (11 males and 2 females, mean age 60 ± 9.9 years) who experienced implant surgery failure at the same site (same tooth extraction area) two or more times in the Department of Oral and Maxillofacial Surgery, Seoul National University Bundang Hospital, between 2004 and 2017 were selected. The medical records on a type, sites, diameter, and length of implants; time and estimated cause of failure; and radiographs were reviewed. Data were collected and analyzed retrospectively, and the current statuses were evaluated. Results: A total of 14 implants experienced failure in the same site more than two times. Twelve implants were placed in the maxilla, while 2 implants were placed in the mandible. The maxillary molar area was the most common site of failure (57.1%), followed by the mandibular molar, anterior maxilla, and premolar areas (14.3% each). The first failure occurred most commonly after prosthetic treatment (35.7%) with an average period of failure of 3.8 months after loading. Ten cases were treated as immediate re-implantation, while the other 4 were delayed reimplantation after an average of 3.9 months. The second failure occurred most commonly after prosthetic treatment (42.9%), with an average of 31 months after loading; during the healing period (42.9%); and during the ongoing prosthetic period (14.3%). In 3 cases (21.4%), the treatment plan was altered to an implant bridge, while the other 11 cases underwent another implant placement procedure (78.6%). Finally, a total of 9 implants (64.3%) survived, with an average functioning period of 60 months. Conclusions: Implants can fail repeatedly at the same site due to overloading, infection, and other unspecified reasons. The age and sex of the patient and the location of implant placement seem to be associated with recurring failure. Type of implant, bone augmentation, and bone materials used are less relevant.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.89-96
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• 2006

Recent ULSI and multilevel structure trends in microelectronic devices minimize the line width down to less than $0.25{\mu}m$, which results in high current densities in thin film interconnections. Under high current densities, an EM(electromigration) induced failure becomes one of the critical problems in a microelectronic device. This study is to improve thin film interconnection materials by investigating the EM characteristics in Ag, Cu, Au, and Al thin films, etc. EM resistance characteristics of Ag, Cu, Au, and Al thin films with high electrical conductivities were investigated by measuring the activation energies from the TTF (Time-to-Failure) analysis. Optical microscope and XPS (X-ray photoelectron spectroscopy) analysis were used for the failure analysis in thin films. Cu thin films showed relatively high activation energy for the electromigration. Thus Cu thin films may be potentially good candidate for the next choice of advanced thin film interconnection materials where high current density and good EM resitance are required. Passivated Al thin films showed the increased MTF(Mean-time-to-Failure) values, that is, the increased EM resistance characteristics due to the dielectric passivation effects at the interface between the dielectric overlayer and the thin film interconnection materials.

• Journal of Trauma and Injury
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• v.26 no.4
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• pp.291-296
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• 2013

Purpose: Prolonged ventilation leads to a higher incidence of ventilator-associated pneumonia (VAP), resulting in weaning failure and increased medical costs. The aim of this study was to analyze clinical results and prognostic factors of VAP in patients with blunt chest trauma. Methods: From 2007 to 2011, one hundred patients undergoing mechanical ventilation for more than 48 hours were divided into two groups: a VAP-negative group, (32 patients, mean age; 53 years, M:F=25:7) and a VAP- positive group, (68 patients, mean age; 60 years, M:F=56:12). VAP was diagnosed using clinical symptoms, radiologic findings and microorganisms. The injury severity score (ISS), shock, combined injuries, computerized tomographic pulmonary findings, transfusion, chronic obstructive lung disease (COPD), ventilation time, stay in intensive care unit (ICU) and hospital stays, complications such as sepsis or disseminated intravascular coagulation (DIC) and microorganisms were analyzed. Chi square, t-test, Mann-Whitney U test and logistic regression analysies were used with SPSS 18 software. Results: Age, sex, ISS, shock and combined injuries showed no differences between the VAP - negative group and - positive group (p>0.05), but ventilation time, ICU and hospital stays, blood transfusion and complications such as sepsis or DIC showed significant differencies (p<0.05). Four patients(13%) showed no clinical symptoms eventhough blood cultures were positive. Regardless of VAP, mortality-related factors were shock (p=0.036), transfusion (p=0.042), COPD (p=0.029), mechanical ventilation time (p=0.011), ICU stay (p=0.032), and sepsis (p=0.000). Microorgnisms were MRSA(43%), pseudomonas(24%), acinetobacter(16%), streptococcus(9%), klebsiela(4%), staphillococus aureus(4%). However there was no difference in mortality between the two groups. Conclusion: VAP itself was not related with mortality. Consideration of mortality-related factors for VAP and its aggressive treatment play important roles in improving patient outcomes.

• Journal of Radiation Industry
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• v.12 no.4
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• pp.325-332
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• 2018

Carotid angiography covering the aortic arch includes contrast-enhanced magnetic resonance angiography (CEA), which is applied to a large region and usually employs contrast media. However, the use of contrast media can be dangerous in infants, pregnant women, and patients with chronic renal failure (CRF). Follow-up patients informed of a lesion may also want to avoid constant exposure to contrast media. We aimed to apply time-of-flight (TOF) angiography to a large region and compare its usefulness with that of CEA. Ten patients (mean age, 58 years; range, 45~75 years) who visited our hospital for magnetic resonance angiography (MRA) participated in this study. A 3.0 Tesla Achieva magnetic resonance imaging (MRI) system (Philips, Netherland) and the SENSE NeuroVascular 16-channel coil were employed for both methods. Both methods were applied simultaneously to the same patient. Three TOF stacks were connected to cover the aortic arch through the circle of Willis, and CEA was applied in the same manner. For the quantitative assessment, the acquired images were used to set the regions of interest (ROIs) in the common carotid artery (CCA) bifurcation, internal carotid artery, external carotid artery, middle cerebral artery, and vertebral artery, and to obtain the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) for the soft tissues. Three radiologists and one radiological resident performed the qualitative assessment on a 5-point scale - 1 point, "very bad"; 2 points, "bad"; 3 points, "average"; 4 points, "good"; and 5 points, "very good" - with regard to 4 items: (1) sharpness, (2) distortion, (3) vein contamination, and (4) expression of peripheral vessels. For the quantitative assessment, we estimated the mean SNR and CNR in each of the 5 ROIs. In general, the mean SNR was higher in TOF angiography (166.1, 205.2, 154.39, 172.23, and 161.95) than in CEA(92.05, 95.43, 84.76, 73.69, and 88.3). Both methods had a similar mean CNR: 67.62, 106.71, 55.9, 73.74, and 63.46 for TOF angiography, and 67.82, 71.19, 60.52, 49.45, and 64.07 for CEA. In all ROIs, the mean SNR was statistically significant (p<0.05), whereas the mean CNR was insignificant (p>0.05). The mean values of TOF angiography and CEA for each item in the qualitative assessment were 4.2 and 4.28, respectively for item 1; 2.93 and 4.55, respectively, for item 2; 4.6 and 3.13, respectively, for item 3; and 2.88 and 4.65, respectively, for item 4. Therefore, TOF angiography had a higher mean for item 3, and CEA had a higher mean for items 2 and 4; there was no significant difference between the two methods for item 1. The results for item 1 were statistically insignificant (p>0.05), whereas the results for items 2~4 were statistically significant (p<0.05). Both methods have advantages and disadvantages and they complement each other. However, CEA is usually applied to a large region covering the aortic arch. Time-of-flight angiography may be useful for people such as infants, pregnant women, CRF patients, and followup patients for whom the use of contrast media can be dangerous or unnecessary, depending on the circumstance.

• Journal of Preventive Medicine and Public Health
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• v.11 no.1
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• pp.24-30
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• 1978

This study was designed to analyse effects of Family Health Workers' activities on the performance of a child immunization program as part of the evaluative research in the community health demonstration project in Kang Wha. Frequent shortcomings of evaluative research are problems in setting evaluative indices, difficulties in interpreting influences of socioeconomic changes due to lack of control and failure of demonstrating association between activity input and program performance. Specific objectives of this study was to improve the frequent shortcoming of evaluative research by isolating the effects of Family Health Workers' activities on the performance of the program through controlling other variables which also influenced the program performance. The target population consisted of 1240 children who were born between Jan. 1971 and Dec. 1975 in Sunwon Myun, and Naega Myun in Kwang Wha Gun, Kyonggi Province. The data were collected in part through 20 Family Health Workers who interviewed the mothers of these children in their villages during Nov. 1977. Part of the data were obtained by summarizing Family Health Workers daily activity records. All data were grouped for each birth cohort according to the 20 villages. Dependent variable of the model is the measle immuinization rate of each village and the independent variables are characteristics of baby, mother, household, travel time to the health subcenter, to Kang Wha Town, and the mean member of visits to the household by Family Health Workers as well as their other related activities and the year of birth of children according to village. The model was analysed by stepwise multiple regression technique. The summarized results show that overall $R^2$ were 39.3% and mean number of Family Health Worker household visits, mean age of mother and mean economic status were significant variables in explaining the immunization rate. Therefore Family Health Workers' activities are one of the significant variables in influencing the increased immunization rate of children in villages of the project area.